This application is based on and claims priority under 35 U.S.C. xc2xa7 119 with respect to Japanese Application No. 2000-020647 filed on Jan. 28, 2000, the entire content of which is incorporated herein by reference.
The present invention generally relates to vehicle seats. More particularly, the present invention pertains to a headrest apparatus for a vehicle seat.
An example of a known headrest apparatus for a vehicle seat is disclosed in Japanese Patent Laid-Open Publication No. 9(1997)-382. The headrest apparatus disclosed in this published application includes a headrest main body comprised of a stay, a headrest frame and a pad. The stay has a pair of vertical stick portions and a horizontal stick portion connecting together both of the vertical stick portions. Each of the vertical stick portions is supported by the seat back of the vehicle. The width of the headrest frame is shorter than the length of the horizontal stick portion. A connecting portion is provided at the bottom end of the headrest frame. This connecting portion connects the headrest frame with the stay in a manner allowing relative rotation via a frictional material. The pad is made from polyurethane and covers the entire headrest frame, the horizontal stick portion of the stay and the upper portions of each of the vertical stick portions. The pad includes two slits portions which allow the stay to move without interfering with the pad, when the headrest main body swings on the horizontal stick portion of the stay.
In this known headrest apparatus, complex injection mold forming dies are needed for forming the pad because two core dies must be inserted into the injection mold forming dies to form the two slits. Therefor, the cost associated with making the headrest assembly is increased and the manufacturing process is relatively time consuming.
Further, based on human engineering research, it is desirable that the passenger head be supported by the head rest with a minimal clearance at the point A as shown in FIG. 1. Also, the surface of the headrest below point A which is along the passenger head profile for supporting the passenger head with wide head rest surface can give the passenger a more comfortable feeling. This head rest arrangement can also provide better absorption of impact in an emergency such as a collision.
To realize the above-mentioned requirements, the connecting portion between the frame of the headrest and the stay must be disposed at the upper portion of the frame. This structure requires longer vertical stick portions covered by the pad. Accordingly, the core dies for forming large width and depth of the slits of the pad become larger. As a result, the manufacture of the headrest apparatus not only becomes expensive, but also makes the mold forming process more complex.
A need thus exists for a vehicle seat headrest apparatus which is not as expensive to manufacture and not as complex in structure, while at the same time providing the desired degree of support and comfort for the seat occupant.
In light of the foregoing, the present invention provides a headrest apparatus for a vehicle seat that includes a stay, a headrest frame and a headrest pad covering the headrest frame. The stay has a pair of vertical posts to be supported by the seat back of the vehicle seat and a horizontal rod connecting the vertical posts. The headrest frame includes a body portion, a connecting portion which hangs the body portion on the horizontal rod in a manner allowing the headrest frame to swing, and spaces between the body portion and the vertical posts to permit the swinging movement of the headrest frame.
According to another aspect of the present invention, a headrest assembly for a vehicle seat includes a stay, a headrest frame, and a headrest pad covering the headrest frame. The stay has a pair of vertical posts and a horizontal rod, with each of the vertical posts being adapted to be supported by a seat back of the vehicle seat and the horizontal rod connecting together the vertical posts. The headrest frame includes first and second frame pieces connected together by a connecting portion. The first and second frame pieces define a body portion. The connecting portion frictionally engages the horizontal rod to permit the connecting portion to be rotated in the forwarded and backward direction relative to the horizontal rod to adjust the position of the headrest frame relative to the stay while also permitting the headrest frame to be maintained at a desired position through the frictional engagement between the connecting portion and the horizontal rod. A part of the body portion surrounds the vertical posts and has an internal dimension in the forward and backward directions that is greater than an outer dimension of the vertical posts to permit the headrest frame to rotate relative to the stay over a range of movement.
In accordance with another aspect of the invention, a method for assembling a vehicle seat headrest assembly involves positioning at least one vertical post of a stay in a channel of one frame piece forming part of a headrest frame while also positioning a horizontal rod of the stay that is connected to the vertical post in a connecting portion of the headrest frame that connects the one frame piece to another frame piece. The one frame piece and the other frame piece are then brought together to cause the connecting portion to encircle and frictionally engage the horizontal rod while the vertical post is positioned in the channel with a space existing between an interior surface of the channel and an exterior surface of the vertical post to permit the vertical post to move in a forward and backward direction in the channel.